Albrich and colleagues1 successfully orchestrated an observational, multinational, multicenter, prospective study of the influence of serum procalcitonin (PCT) levels on the care of patients with lower respiratory tract infections (LRTIs). Specifically, does access to PCT levels plus the use of an interpretative advice algorithm influence the duration of antibiotic therapy? The comparison was between patients whose physicians were compliant with the algorithm vs patients whose physicians were noncompliant. Noncompliance was defined as failure to follow the algorithm by either initiation of antibiotic therapy or failure to discontinue therapy despite low PCT levels in the absence of predefined criteria that allowed the algorithm to be overruled. In short, the algorithm advice was overruled and managed based on clinical judgment.